Thermodynamics of Protonation and Sodium Binding of Sulfate in Concentrated NaCl and CsCl Solutions Studied by Raman Spectroscopy

Kratsis, Steven; Hefter, Glenn; May, Peter M.; Sipos, Pál

doi:10.1071/ch00011

Cited by 11 publications

(8 citation statements)

References 14 publications

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“…Recent simulation studies 29 have suggested that two types of hydration occur for the alkali metal cations, which the authors termed electrostatic (hydrophilic) ion solvation and cage formation (hydrophobic hydration). The former predominates with the smaller cations whereas the latter becomes important for the larger cations, resulting, for example, in a maximum in the solvation entropies as a function of ion size. , Circumstantial evidence for greater-than-expected binding of simple ligands by Cs + has also been obtained by Raman studies. , In particular, it was postulated that the extent of contact ion-pair (CIP) formation increased with increasing cation size as a result of the decreasing strength of the (primary) hydration sphere . This can occur even if the overall formation constant shows the opposite trend.…”

Section: Resultsmentioning

confidence: 99%

“…29,42 Circumstantial evidence for greater-than-expected binding of simple ligands by Cs + has also been obtained by Raman studies. 43,44 In particular, it was postulated that the extent of contact ion-pair (CIP) formation increased with increasing cation size as a result of the decreasing strength of the (primary) hydration sphere. 44 This can occur even if the overall formation constant shows the opposite trend.…”

Section: Possible Ion Pairing In Cscl(aq)mentioning

confidence: 99%

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Dielectric Spectroscopy of Aqueous Solutions of KCl and CsCl

2003

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Results of a dielectric relaxation study of the aqueous solutions of KCl and CsCl at 25 °C are reported using measurements with a vector network analyzer (0.2 ≤ ν/GHz ≤ 20) and with waveguide interferometers (27 ≤ ν/GHz ≤ 89). Similar to previously reported data for NaCl, the spectra of both salts are well fitted by a Cole−Cole equation, although a double-Debye model is competitive at intermediate CsCl concentrations. The impact of the solute on the water structure, reflected in a decrease in the bulk-water relaxation time with rising electrolyte concentration, decreases in the sequence NaCl > KCl > CsCl and appears to be proportional to the surface-charge density of the cation. The interactions of K+ and Cs+ with their hydration shells are too weak to cause irrotational bonding of H2O molecules. It is argued that CsCl exhibits weak ion pairing, although the data are not sufficiently accurate to determine the extent of association and the nature of the ion pair formed.

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Section: Resultsmentioning

confidence: 99%

Section: Possible Ion Pairing In Cscl(aq)mentioning

confidence: 99%

Dielectric Spectroscopy of Aqueous Solutions of KCl and CsCl

2003

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“…Elevated temperature Raman measurements were performed using a custom-made attachment (Ventacon, UK) as described elsewhere. 33 To check the reproducibility of the data, a few spectra were measured using a Bruker RFS-100 near IR FT-Raman spectrometer with Nd:YAG laser and Ge-diode detector as described elsewhere. 5, 6 The results were in quantitative agreement with those reported here.…”

Section: Methodsmentioning

confidence: 99%

Quantitative determination of an aluminate dimer in concentrated alkaline aluminate solutions by Raman spectroscopy

2006

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Raman spectra of concentrated alkaline aluminate solutions in various M'OH media (M'(+) = Na(+), K(+), Cs(+) and (CH(3))(4)N(+)) have been investigated systematically as a function of concentration and water activity, a(w). All spectra at [Al(III)](T) < or = 1 M and at 0.1 < or = [M'OH](T)/M < or = 5 (where the square brackets denote concentrations and the subscript T totals) exhibit one significant Raman mode in the low frequency region, at ca. 620 cm(-1), due to the symmetric Al(OH)(4)(-) stretch. At higher [Al(III)](T) and [M'OH](T) new modes appear at 530-550 and 700-720 cm(-1). The intensities of these new bands depend on [Al(III)](T) and a(w) but are independent of [OH(-)](T) and are only slightly cation-dependent. All three bands shift towards higher wavenumbers at [M'OH](T) > 10 M, probably due to ion-pairing. Spectra at [M'OH](T) < 10 M have been interpreted quantitatively by assuming that the integrated peak area of the 620 cm(-1) mode is linearly proportional to [Al(OH)(4)(-)] at constant a(w) and that the only significant equilibrium in these systems is the formation of a dimer that can be represented as (Al(OH)(4))(2)(2-)(aq), although it may exist in an oxo-bridged form such as [(HO)(3)Al-O-Al(OH)(3)](2). The (aquated) species Na(+), OH(-), Al(OH)(4)(-), the dimer, and their ion-pairs, were sufficient to interpret all the Raman observations. No evidence was found for various other species that have been claimed to exist in concentrated alkaline aluminate solutions.

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“…Various authors studied [4][5][6][7][8][9][10], mainly by Raman spectroscopy, the distribution of HSO 4 − , SO 4 2− and of the molecular H 2 SO 4 in aqueous sulphuric acid solutions from 0 to 100 wt.% in acid, generally at 298.15 K. Spectra indicate that the molecular form appears only at acid concentrations larger than 20 M (M ≡ mol/L).…”

Section: Speciation Of Aqueous Sulphuric Acidmentioning

confidence: 99%

Study of titanium(IV) speciation in sulphuric acid solutions by FT-Raman spectrometry

Baillon¹,

Provost²,

Fürst³

2008

Journal of Molecular Liquids

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The effects of the addition of titanium(IV) to aqueous solutions of sulphuric acid were studied by FT-Raman spectroscopy. Solutions containing 0 M to 4.01 M of titanium(IV) and 1.98 M to 6.17 M of sulphuric acid were analysed. A new peak, characteristic of titano-sulphate complexes, has been observed, in addition to the peaks characterising ions SO 4 2− and HSO 4 −. Free HSO 4 − and SO 4 2− concentrations have been determined from the Raman peak areas. From mass balance it was deduced that two complexes are present in the solution: [Ti(OH) 2 SO 4 ] (aq) and [Ti(OH) 2 (SO 4) 2 ] 2− (aq). Their apparent constants of formation have been estimated.

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Thermodynamics of Protonation and Sodium Binding of Sulfate in Concentrated NaCl and CsCl Solutions Studied by Raman Spectroscopy

Cited by 11 publications

References 14 publications

Dielectric Spectroscopy of Aqueous Solutions of KCl and CsCl

Dielectric Spectroscopy of Aqueous Solutions of KCl and CsCl

Quantitative determination of an aluminate dimer in concentrated alkaline aluminate solutions by Raman spectroscopy

Study of titanium(IV) speciation in sulphuric acid solutions by FT-Raman spectrometry

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